The present invention relates generally to a method for manufacturing a cooling device, and more particularly to a method for manufacturing a cooling device. The heat pipe of the cooling device contacts the heat source directly.
The operation of electronic products, such as personal computer, light emitting laser diode or dynamic transistor, will dissipate heat. For the recently developed electronic devices, more and more heat is generated therefrom. Cooling technology thus becomes one of the key technologies of electronic industry. Typical cooling devices for electronic products are divided into two categories. One type of the cooling devices includes a cooling body installed directly on the heat generating electronic device. The other type of the cooling devices includes a fan for lowering the temperature in the housing of the electronic device.
The cooling device installed on electronic products is normally made of materials of high heat conductivity. For example, copper or aluminum is used to fabricate a flat base, a flat heat pipe or a cylindrical heat pipe. The heat pipe is a hollow container evacuated to certain degree of vacuum, wherein a working fluid is properly enclosed. Since the container is evacuated, the working fluid is easily evaporated due to the absorbed heat.
The working principle of the heat pipe described in the following. In general, the heat pipe includes an absorption end and a cooling end. The absorption end contacts the heat source and absorb heat generated therefrom. The absorbed heat is transferred to the working fluid, thereby evaporating the working fluid. The working fluid is then transported to the cooling end and is condensed back to liquid. The condensed working fluid then returns to the absorption end, thereby forming a heat transfer cycle. The circulation of working fluid within the heat pipe is enhanced by gravity or capillary effect. The former disposes the absorption end lower than the cooling end, while the later employs retaining grooves, a metallic web or a porous material formed on the inner wall of the container. Therefore, a huge amount of heat is transferred and dissipated by the phase transition of the working fluid enclosed in the heat pipe.
Further, a heat dissipater can also be used to dissipate heat generated from an electronic device. The heat dissipater includes a heat conductor and a set of cooling fins. Conventional cooling fins includes a set of leaves extended outward, which is connected to the heat conductor by copper soldering or extrusion. The cooling fins and the heat conductor of the heat dissipater are made of materials of high heat conductivity.
Since the heat conductivity of the heat pipe is hundreds of times higher than that of copper, the price thereof is for sure much higher. If a few coupled heat pipes are required to install on a heat generating device, the cost so rendered will certainly become an obstacle for commercializing the product. On the other hand, the advancement of electronic technology gives rise to electronic products that generate more and more heat. Simply using the heat dissipater composed of a heat conductor and cooling fins can not meet the heating requirement. Therefore, a compromised heat pipe cooling device is developed, which includes a heat conductor, a set of cooling fins and a heat pipe. The cooling end of the heat pipe penetrates through the hole formed on each cooling fin. In addition, a plurality of parallel grooves are formed on the heat conductor, thereby soldering with the absorption end of the heat pipe. Consequently, the heat conductor contacting a heat generating electronic device will transfer the heat from the electronic device to the heat pipe and the cooling fins.
However, the conventional heat pipe cooling device requires a soldering layer for connecting the heat pipe and the heat conductor. The soldering process requires heating the heat pipe and the heat conductor, which will form a black copper oxide layer on the surface of the copper heat pipe. Therefore, an additional oxidation reduction process is necessary to recover to its original color, which will increase the time and the cost for fabrication. Moreover, the soldering material will reduce the heat conductivity of the heat conductor. Finally, since the heat pipe, which has a heat conductivity of the heat pipe is much larger than that of the heat conductor, is not adhered to the heat generating electronic device, the performance of such a conventional cooling device is thus very much restricted.